This invention relates generally to soft rawhide and a method of forming soft rawhide and more particularly to an edible chew toy made of chopped rawhide, for pets, such as dogs.
Rawhide products originate from the natural skins of animals such as cows. Other animal skins, such as pig, goat and water buffalo skins can also be used. To form rawhide, a cow or other animal hide is split. The top grain is generally tanned and formed into leather products. The bottom half of the hide is generally kept in its natural "raw" state. Hides in such natural, untanned state, are generally referred to as rawhide. One common use for rawhide is the production of chemicals such as gelatin. Another important use for rawhide is the manufacture of edible chew toys for pets, such as dogs.
One characteristic of a pet chew toy is that it should be nontoxic. Thus, rawhide chew toys should not include dangerous substances such as formaldehyde and other preservatives which prevent the rawhide from becoming contaminated by bacteria, microbes, maggots and the like. A rawhide chew toy also cannot contain many of the processing chemicals commonly used in the tanning of leather which make the leather soft. Not only could these be unhealthy to a dog, but training a dog to chew on a toy which smells like leather could fool a dog into thinking that it is acceptable to chew on a shoe or leather handbag.
In order to make rawhide chew toys acceptably resistant to contamination, rawhide chew toys are commonly sold in a dehydrated state. An acceptably low moisture content can lead to a safe or stable water activity. Thus, if the water activity of the rawhide article is too high, there is a possibility that the chew toy will be contaminated by mold, bacteria and the like or otherwise become unsanitary and potentially harmful for the pet. Thus, many rawhide chew toy products contain less than about 13% moisture in order to have an acceptable water activity below about 0.75.
Water activity is defined by Encyclopedia of Food Science, AVI Publishing as the ratio of the vapor pressure exerted by the water contained in the product to the vapor pressure of pure water at the same temperature. The lower the water activity of a product, the less susceptible that product is to the growth of bacterial, fungal and yeast organisms. Fruits, bread and meat all have water activities above 0.95. In contrast, crackers, cereal and sugar can have a water activity as low as 0.1.
Conventional rawhide chew toys have drawbacks. When made with acceptably low moisture, the product can be extremely hard and rigid. Thus, old dogs, small dogs or dogs with tooth problems are often unable to enjoy a conventional low moisture content, naturally hard, rigid, rawhide chew toy. Many dog owners also find conventional hard rawhide toys to be unpleasant to handle after a pet has been chewing the toy.
One form of a rawhide chew toy is made from chopped rawhide, which is subsequently formed into a desirable shape, such as that of a bone. However, conventional chopped rawhide chew toys suffer from drawbacks of conventional rawhide products, such as undesirable rigidity.
Accordingly, it is desirable to provide an improved rawhide product which is soft, sanitary, safe for a pet to eat and which can be formed into a desirable shape.